.top {
    background-image: url("../img/banner_qtah.jpg");
    background-size: 100% 100%;
    height: 500px;
    /*width: 1920px;*/
    /*    默认宽度就是外面div的宽度*/
    /*height: calc(1000 * 808px / 1920);*/
    color: white;
}

.logo-div {
    height: 141px;
}

.height-50 {
    height: 50px;
}

.nav {
    line-height: 50px;
}

.nav > div {
    padding: 0 20px;
    cursor: pointer;
}

.nav > div:hover {
    background-color: white;
    color: rgb(230, 145, 55);
}

.ad {
    height: calc(500px - 141px - 50px);
}

.ad > div > div:nth-child(1) {
    font-size: 40px;
    line-height: 70px;
}

.ad > div > div:nth-child(1) > div:nth-child(2) {
    margin: 0 10px;
}

.ad > div > div:nth-child(2) {
    font-size: 10px;
}

.ad > div > div:nth-child(2) > div {
    /*margin: 5px 0 ;*/
    line-height: 20px;
}

.ad > div > div:nth-child(3) {
    color: rgb(230, 145, 55);
    font-size: 30px;
}

/*div[pw]{*/
/*    color: white;*/
/*    font-size: 20px;*/
/*}*/
.pw {
    color: white;
    font-size: 20px;
}
